1. Field
The inventive concept relates to a semiconductor memory device, and more particularly, to a semiconductor memory device having an improved layout of a well with a sense amplifier circuit therein.
2. Description of the Related Art
In general, a semiconductor memory device includes a sense amplifier circuit for detecting data written in a plurality of memory cells. The sense amplifier circuit needs to be highly sensitive to stably detect the data. Recently, a design of the semiconductor memory device has become more complicated and a manufacturing process thereof has become minutely detailed according to user demand, which causes deterioration of the sensitivity of the sense amplifier circuit. For example, due to an influence of other wells adjacent to or crossing a well, in which transistors included in the sense amplifier circuit are formed, a threshold voltage of transistors of the sense amplifier circuit formed in a boundary of wells varies. In particular, such a variation in the threshold voltage may be problematic in a region including the sense amplifier circuit and other circuits crossing the sense amplifier circuit.